Monitoring bubble size distribution using pressure fluctuations.

Abstract

Bubble size and distribution are key monitoring parameters for the heat and mass transfer performance in gas-liquid bubble columns and gas-liquid-sold fluidized bed processes. Many of the techniques currently in use are expensive, time consuming and intrude into the systems. Physical intrusion disrupts the original flow of the bubbles and affects the results obtained.

Predicting bubble size using pressure fluctuations caused by bubbles is becoming a popular method. Power spectral analysis and chaotic theory analysis are techniques developed in recent years. These “batch” techniques are unable to provide continuous monitoring of the bubble sizes due to post data processing required. Nonetheless, studies involving dynamic gas disengagement have shown that it is possible to read bubble size distributions from pressure fluctuations. Pressure fluctuation is a promising method due to its ease and low cost of implementation, non-intrusive nature and potential online-monitoring capability.

This study investigates the feasibility of using the direct pressure fluctuation signal to predict bubble size and its distribution. The proposed method was tested experimentally and verified using the photographic method. The basis of comparison used was the bubble cap diameter and volume diameter, the volume diameter showed accuracy of up to 89%.